Detection of simulated inflicted metaphyseal fractures in a fetal pig model: Image optimization and dose reduction with computed radiography

Purpose: To prospectively determine in a fetal pig model whether diagnostic performance comparable to that of high-detail screen-film imaging can be achieved with computed radiography for the detection of simulated classic metaphyseal lesions (CMLs), by using Faxitron digital images as the reference standard, and whether radiation dose reduction is possible. Materials and Methods: This study was granted exempt status by the institutional review board and the animal care and use committee. Fractures simulating the CML were produced in distal femurs of 20 deceased fetal pigs. Twenty normal femurs served as control femurs. Femurs were imaged with a standard single-side-read 100-mu m pixel sampling imaging plate (IP), a high-resolution dual-side-read 50-mu m pixel sampling IP, and a high-detail screen-film imaging system. Eight tube current-time product settings (0.5-10.0 mAs) and two tube voltage selections (56 and 70 kVp) were employed. Two pediatric radiologists evaluated 920 images for fracture by using a five-point Likert scale. Area under the receiver operating characteristic curve (A(z)) values for the imaging systems were compared by using non-parametric X-2 tests (all P < .05). Results: For pooled rater data, performance of computed radiography was comparable to that of screen-film imaging, and superior performance (P = .04) was achieved with the more experienced rater. The Az value tended to increase as the tube current-time product setting was increased. Within each system, there was no significant difference in Az values for all images obtained at 56 and 70 kVp (dual-side-read IP, P = .63; single-side-read IP,P = .25; screen-film imaging system, P = .5). At 56 kVp, a dose reduction of up to 69% was achieved, and accuracy of computed radiography was comparable to that of screen-film imaging. Conclusion: Findings in this study suggest that computed radiography can replace screen-film imaging in the detection of CMLs and may permit dose reduction.